[Wikipedia:Keyboard_layout] has images of keyboard layouts from different countries.

[http://www.microsoft.com/globaldev/reference/keyboards.mspx] can display different keayboard layouts.

Also see [OLPC keyboards].

!US

All special markup is easily available.

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!UK

All proposed wikicreole markup characters are visible on UK keyboards; accessible either by single key press or Shift+ key press.

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!PL

The backslash (\), pipe (|), square brackets ([[]]), curly braces ({}) and single quotation mark (') require pressing an additional function key on polish(214) keyboard. The more popular polish (programmers) keyboard layout is practically identical to the US layout.

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!DE

Nearly all markup needs an additional key, either Shift+key or AltGr+key. But at least all the symbols are visible on the keyboard. 

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!FR-fr (AZERTY), FR-ch (QWERTZ)

All ASCII characters (32-127) are available. Some markups need an additional key (AltGr+key, or Alt+key on Mac). A few of them (the potential ^ and ~) must be pressed twice since they are considered as modifiers for other letters.

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!FR-ca, EN-ca (Canadian multilingual)

The Canadian French keyboard comes in several flavors. Nevertheless, all proposed markups are available. Some markups need an additional key (Shift+key or AltGr+key). Some of them (depending on the chosen layout) must be pressed twice since they are considered as modifiers for other letters. There is a problem however from French Canadians purchasing US-English keyboards (most of them are outside of the province of Quebec). If they change their layout for a French Canadian one, important markups (like square brackets ([[]), greater/lesser-than (<>), slash (/), curly braces ({})) are not at their respective places anymore. These people [must] switch back and forth between two layouts.

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!RU

The only punctuation characters available on the russian keyboard are: 
{{{
 !"№;%:?*()_+-\/.,
}}}

All other characters are only available after switching to the us layout.

-- RadomirDopieralski, 2007-01-18